Technological Field
The present invention relates to an electrophotographic image forming apparatus and a method for controlling the image forming apparatus.
Description of the Related Art
An electrophotographic image forming apparatus has a fixing device for fixing toner on a recording material. For example, the fixing device includes a pair of fixing rotary members so that the recording material on which toner has been transferred is passed between the members and the toner is thereby heated and pressed against the recording material. In this fixing device, when a recording material with the same width is passed continuously, scarring or edge damage occurs at a position where a side edge of the recording material passes in the fixing device and if a wider recording material is passed there afterward, a formed image may deteriorate.
As a solution to this problem, a technique is known in which if a cumulative sum of values obtained by multiplying the length of the recording material passed through the fixing device by a weighting factor corresponding to at least one of the width and basis weight of the recording material is a threshold or more, the surface shape of the fixing member is adjusted to prevent deterioration of the formed image (see Patent Literature 1 below).